DuckDB: in-process SQL OLAP (column store) database

DuckDB - An in-process SQL OLAP database management system

Simple
In-process, serverless
C++11, no dependencies, single file build
APIs for Python/R/Java/…

Feature-rich
Transactions, persistence
Extensive SQL support
Direct Parquet & CSV querying

Fast
Vectorized engine
Optimized for analytics
Parallel query processing

Free
Free & Open Source
Permissive MIT License